Cysts Flashcards
What is the definition of a cyst
pathological cavity which contains fluid, semifluid or gaseous content and is not created by the accumulation of pus
What are the signs/symptoms of cysts
possibly swelling
impeded eruption
often asymptomatic unless infected
What is the first line x-ray for a cyst
periapical
When may OPT/occlusal be taken for a cyst
When the cyst is too large to be captured fully in a periapical
What supplemental views may be taken in addition to plain film x-ray
CBCT/facial radiographs e.g PA mandible/occipitomental
What radiographic features should be noted in a report when reporting on a cyst
location
shape
margins
locularity
multiplicity
effect on surrounding anatomy
What may a lack of margins be indicative of
infection
lack of corticated margin
What are cysts classified based on
structure
origin
pathogenesis
How can cysts be classified by structure
epithelial lined vs non epithelial lined
How can cysts be classified by origin
odontogenic
non-odontogenic
How can cysts be classified by pathogenesis
developmental
inflammatory
What can odontogenic cysts be split into
developmental and inflammatory
What are the main developmental odontogenic cysts
dentigerous (& eruption cysts)
odontogenic keratocyst
Lateral periodontal cyst
What are the main inflammatory odontogenic cysts
radicular cyst (& residual cyst)
inflammatory collateral cysts
What are the two types of inflammatory collateral cysts
paradental cyst
buccal bifurcation cyst
What is an example of non-odontogenic developmental cyst
nasopalatine duct cyst
What is an example of other non-odontogenic cyst
unknown cause
solitary bone cyst
aneurysmal bone cyst
What is unique solitary bone cyst and aneurysmal bone cyst
both have no epithelial lining
What is the most common odontogenic cyst
radicular
What are some features of odontogenic cysts
- found in tooth bearing areas
- all epithelial lined
- most common cause of bony swellings in the jaw
Where can the odontogenic cyst epithelial lining originate from
rests of mallasez
rests of serres
reduced enamel epithelium
What is a radicular cyst
it is an inflammatory odontogenic cyst
Why are sensibility testing important in diagnosis for radicular cyst
- the tooth must be non vital
How does a radicular cyst form from a non-vital tooth
non-vital tooth forms chronic apical infection
chronic apical infection results in periapical granuloma (progression from acute apical abscess/chronic sinus/acute apical periodontitis)
then progresses to radicular cyst
When measuring the size of the radiolucency on the x-ray, what measurement would point to a radicular cyst rather than a PA granuloma
> 15mm
indicative of a radicular cyst
What are the radiographic features of a radicular cyst
well defined
round/oval
corticated margin is continuous with the lamina dura
larger lesions may displace adjacent structures
What can a long standing radicular cyst result in
external root resorption
contain dystrophic calcification
What is dystrophic calcification
can occur in longstanding radicular cysts
this is the deposition of calcium salt in degenerated tissues in the absence of systemic mineral imbalance
What type of epithelium is found in the epithelial lining of a radicular cyst
non keranizied stratified squamous
variable thickness
What cystic features can be seen on the histopathology for radicular cyst
- epithelial lining (often incomplete)
- connective tissue capsule
Where do the cells of a radicular cyst originate from
rests of mallasez
On a histological level, how does radicular cyst form
- rests of mallasez scells proliferate in the peri-apical granuloma, when this happens the centre of the granuloma is cut off from the blood supply resulting in central necrosis
- may also form by epithelium surrounding the fluid filled area
What type of growth do we usually see in radicular cysts
unicentric balloon type growth
How do radicular cysts continue growth
histology
centre of the cyst draws in water from the surrounding areas by osmosis and puts pressure on surrounding bone resulting in resorption
inflammation results in release of inflammatory mediators which increases the cyst size
What are the key histological features that are distinct in radicular cysts
- variable inflammation
- cholesterol clefts
- mucous metaplasia
- hyaline/rushton bodies
What are cholesterol clefts
radicular cysts
- derived from breakdown of RBC as a result of haemorrhage
- may be few in number or form large mural nodules
- usually associated with epithelial discontinuities and project into the cyst lumen
- cholesterol crystals may be found in the cyst fluid
What are hyaline/rushton bodies
radicular cysts
found in the epithelial lining
appear as eosinophilic bodies of varying size and shape
of unknown origin
What are the 2 variants of radicular cyst
- residual cyst
- lateral radicular cyst
What are residual cysts
radicular cysts
this is when a residual cyst persists after loss of the tooth/post-RCT (if successful)
What are lateral radicular cysts
radicular cysts
*radicular cysts are associated with lateral canals
located at the side of the tooth rather than the apex
What type of cyst is an inflammatory collateral cyst
inflammatory odontogenic cyst
What is an inflammatory collateral cyst associated with
vital tooth
What are the two main types of inflammatory collateral cysts
paradental cyst
buccal bifurcation cyst
What is a paradental cyst
typically occurs at the distal aspect of partially erupted third molars
What is a buccal bifurcation cyst
typically occurs at the buccal aspect of the mandibular firs tmolar
crown of the tooth will start to tilt buccally
What type of cyst is a dentigerous cyst
developmental odontogenic cyst
What type of cyst is a dentigerous cyst
developmental odontogenic cysts
What is a dentigerous cyst associated with
crown of unerupted tooth and usually impacted tooth
What is the dentigerous cyst derived from
cystic change of the dental follicle
What are the radiographic features of a dentigerous cyst
corticated margin attached to CEJ of the tooth
may displace involved tooth
tends to be symmetrical initially however larger cysts may expand unilaterally
variable displacement of the bone
What are histological features of dentigerous cysts
epithelial lining
islands of odontogenic epithelium in the wall of the dentigerous cyst
What type of epithelium will be seen in dentigerous cyst
non keratinized stratified squamous
When may a dentigerous cyst resemble a radicular cyst histologically
if inflamed
How can you differentiate a dentigerous cyst from the dental follicle
measure distance from crown to the edge of the follicle
What measurements would make us think of a dentigerous cyst when trying to differentiate between it and an enlarged follicle
consider a cyst if >4mm
assume a cyst if >10mm
if follicle asymmetrical, consider cyst
What is a variant of the dentigerous cyst
eruption cyst
What makes the eruption cyst different from the dentigerous cyst
it is contained within soft tissue, not bone
What type of cyst is an odontogenic keratocyst
developmental odontogenic cyst
Is the keratocyst associated with the teeth
no
What type of growth is seen in odontogenic keratocyst
aggressive
What is the most ‘dangerous’ feature of the odontogenic keratocyst
has high recurrence
What are the radiographic features of the odontogenic keratocyst
often have scalloped margins
1/4 multilocular
often causes displacement of adjacent teeth
characteristic expansion
What is the characteristic expansion of the odontogenic keratocyst
enlarges significantly in the medullary bone before displacing cortical bone aka expands a lot in the emsial distal direction before spreading buccal/lingually
What type of biopsy is taken for an odontogenic keratocyst
aspirational biopsy
What will be diagnostic characteristic features are seen in the OK aspirational biopsy
greasy fluid
keratotic squames
low soluble protein content compared to other cysts (<4g% is diagnostic)
What histological features will be seen in a keratocyst
palisades
parakeratosis
cell nests
daughter cysts
OK histology
What are palisades
refer to the neat stacking of parallel rows of elongated nuclei
What is parakeratosis
- incomplete maturation of epidermal keratinocytes resulting in abnormal retention of nuclei in the stratum corneum
What is orthokeratosis
thickening of the keratin layer with preserved keratinocyte maturation
When may the keratin layer not be present in an odontogenic keratocyst
if it is inflamed
Seen in the OK histology
What are cell nests
epithelium seperating from the walls resulting in islands of epithelium
What can cell nests turn into
daughter cysts
responsible for high recurrence
What syndrome presents with multiple odontogenic keratocysts
basal cell naevus syndrome
What other features do those with basal cell naevus syndrome present with
multiple basal cell carcinomas on the skin
palmer and plantar pitting on the hands and feet
calcification of intracranial dura mater
histologically the cysts dont differ to the non syndromic form
What age is odontogenic keratocyst most common in
teenagers/YA
What gender is odontogenic keratocyst most common in
males
Which jaw is odontogenic keratocyst most common in
mandible
Are odontogenic keratocysts more common anterior or posterior
posterior
What age group are dentigerous cysts most common in
teenagers/YA
What gender are dentigerous cysts most common in
males
What jaw is dentigerous cysts most common in
mandible
What age group is radicular cysts most common in
30s to 40s
Which gender is radicular cyst most common in
equal split
What type of cyst is nasopalatine duct cyst
developmental non odontogenic keratocyst
Where does the nasopalatine duct cyst arise from
nasopalatine duct epithelial remnants
Where is the nasopalatine duct
it runs through the nasopalatine canal which starts at the base of the anterior nasal cavity and goes through the maxilla, opening up at the incisive fossa
Where does the nasopalatine duct cyst occur
always anterior maxilla
What age group is nasopalatine duct cyst most ommon in
30s to 50s
Which gender is nasopalatine duct cyst most common in
males
Which jaw is the nasopalatine duct cyst most common in
maxilla
anterior
What is the presentation of nasopalatine duct cyst
- often asymptomatic
- patient may C/O salty discharge
- larger cysts may displace teeth and cause swelling in the palate
- always involves the midline but not always symmetrical
What are the radiographic features of nasopalatine duct cyst
- corticated radiolucency between/over roots of central incisors
- generally unilocular (rare to be multilocular)
- may appear as heart shaped due to superimposition of anterior nasal spine - characteristic
- can be asymmetrical
What is the ideal view for nasopalatine duct cyst
PA/maxillary occlusal
When is CBCT indicated for nasopalatine duct cyst
- if better visualisation of cyst needed for surgical planning
What are the histological features of nasopalatine duct cysts
- variable epithelial lining
- may be made up of non-keratinized stratified squamous epithelium & modified respiratory epithelium
What type of epithelium is respiratory epithelium
ciliated pseudostratified columnar
How does the incisive fossa appear on a radiograph (doesnt always appear)
- oval shaped radiolucency
- typically not corticated
How can we decide if a radiolucency is a nasopalatine cyst or incisive fossa
consider the transverse diameter (only if the px is asymptomatic, otherwise lean towards cyst)
* <6mm = assume incisive fossa
* 6-10mm = consider monitoring (x-ray in 3-6 months)
* >10mm = suspect cyst
What age group is solitary bone cyst most common in
teenagers
What jaw are solitary bone cysts most common in
mandible
What gender are solitary bone cysts most common in
males
What gender are solitary bone cysts most common in
males
What is a solitary bone cyst
non odontogenic cyst
no epithelial lining
What is a solitary bone cyst aka
simple/traumatic/haemorrhagic bone cyst
What can a solitary bone cyst occur in association with
other bony pathology e.g fibro-osseous lesions
What is the clinical presentation for solitary bone cyst
usually asymptomatic
rarely any pain or swelling
What are the radiological features of solitary bone cyst
- majority in the premolar region of the mandible
- can occur in non tooth bearing areas
- variable definition and cortication
- may have scalloped margins giving a pseudolocular appearance
- may project up between roots of adjacent teeth
What is a stafne cavity
not a cyst
often mistaken as one
it is depression of the bone
Where do stafne cavities usually occur
mandible
usually lingual
usually in angle or body
What do stafne cavities contain
salivary/fatty tissue
What is teh presentation of stafne cavity
asymptomatic
rarely displaces adjacent structures
What is the radiographic features of stafne cavity
well defined
often corticated margins
What is the first line biopsy for a cyst
aspirational
What is an aspiration biopsy
drainage of contents
What can be captured in an aspiration biopsy
- air
- blood
- pus
- cyst fluid
How can cyst fluid aid diagnosis
clear/straw coloured fluid = inflammatory/developmental cyst
thick white fluid = keratocyst
What is the purpose of the incisional biopsy
it is partial removal
aims to obtain lining sample
What is the method for incisional biopsy
- LA
- select area where lesion appears most superficial
- raise mucoperiosteal flap
- remove bone as required
- incise and remove section of lining
- may be combined with marsupialisation
What is the decision to take a biopsy dependant on
- size
- site
- radiographic characterisation
What is a excisional biopsy
full removal
following enucleation most likely
What are the 2 tx options for cyst
enucleation
marsupialisation
What is enucleation
- all of the cystic lesion removed
- usually under GA
What are the advantages of enucleation
- preferred option
- whole lining cna be examined pathologically
- primary closure achieved = better healing
- less aftercare required
What are the disadvantages of enucleation
- risk of mandibular fracture with very large cysts, marsupialisation preferred
- dentigerous cyst where loss of tooth is undesirable
- old age/ill health, GA often reqiured for enucleation
- blood clot filled cavity forms after removal and can get infected
- damage to adjacent structures e.g IAN
What is the method for enucleation
- raise mucoperiosteal flap
- expose bone
- remove cyst
- close mucoperiosteal flap
What are the indications for marsupialisation
- if enucleation would damage adjacent structures
- difficult to access area
- may allow for eruption of teeth that are impacted by dentigerous cyst
- elderly/medically compromised patient unable to withstand extensive surgery
- very large cysts which would risk jaw fracture if enucleation performed
- can combine with enucleation later on when cyst shrinks
What are contraindications to marsupialisation
- opening may close and cyst may reform - obturator required to keep marsupialsation windows open
- complete lining ont available for histology
- hard to keep clean, aftercare required
What are the advantages of marsupialisation
- simple to perform
- under LA
- may spare vital structures
What factors does tx depend on
- nature of lesion
- age of px
- degree of involvement
- radiographic characterisation
- histopathology
